Pluto was square Haumea, within 1 degree, from the 22nd April to the 7th of July this year. This was the first contact between the planets for this aspect and there was no exact hit. The square will first be exact on the 8th May next year, and then on another 5 occasions over the next 4 years, so this aspect will be a feature of the early 2020's.
In that time, Haumea will transit from Libra to Scorpio, and Pluto will transit from Capricorn to Aquarius. So it looks like major change is on the way and we can see what the nature of that change might be, by looking at events on the 27th May when the square was at it's closest, which was 34 minutes.
That was the time of the state hijacking by Lukashenko in Belarus, who kidnaped an exiled young media executive, as he attempted to put down (Pluto) a popular rebirth (Haumea) in that country. So we are likely to see these sort of power struggles between autocrats and the social renewal process in various parts of the world reach crisis points at each of the squares.
And that day Big Oil had a major defeat as activist shareholders in Exon Mobil elected a couple of board members who pledged to steer the company away from oil and towards renewables. This suggests that the squares will force the move from fossil fuels (Pluto) to renewables (Haumea).
So, while these squares will be challenging, these are the challenges we need for humanity to make the transition to a new way of living in harmony with the planet. The danger, it must be said, is that both Pluto and Haumea talk about potentially violent or catastrophic change.
The Hawaiian islands are volcanic and they are born in eruption, so the rebirth Haumea talks about can be earth shattering in its nature, particularly in the moment of rebirth, and particularly if the pressure for change has built up over time. Pluto, as we know, is very similar.
Alan, considering the Sabian themes for the two degrees is also instructive. Pluto at 27 Capricorn--"Pilgrims climbing the steep steps towards a mountain shrine"--implies a narrow, but well-established path towards a supposedly transcendent destination; Haumea's degree--28 Libra--depicts "A [person] becoming aware of spiritual forces surrounding and assisting" them. The first image is of individual strength and determination ; the second of the individual as part of a larger, collective whole. There is a shift from egoistic consciousness to a more holistic view.